Method for producing semiconductor device and semiconductor device

ABSTRACT

A SGT production method includes a step of forming first and second fin-shaped silicon layers, forming a first insulating film, and forming first and second pillar-shaped silicon layers; a step of forming diffusion layers by implanting an impurity into upper portions of the first and second pillar-shaped silicon layers, upper portions of the first and second fin-shaped silicon layers, and lower portions of the first and second pillar-shaped silicon layers; a step of forming a gate insulating film and first and second polysilicon gate electrodes; a step of forming a silicide in upper portions of the diffusion layers formed in the upper portions of the first and second fin-shaped silicon layers; and a step of depositing an interlayer insulating film, exposing and etching the first and second polysilicon gate electrodes, then depositing a metal, and forming first and second metal gate electrodes.

RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119(e), this application claims the benefit ofthe filing date of Provisional U.S. Patent Application Ser. No.61/566,244 filed on Dec. 2, 2011. The entire content of this applicationis hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device.

2. Description of the Related Art

The degree of integration of semiconductor integrated circuits, inparticular, integrated circuits using MOS transistors, has beenincreasing. With the increasing degree of integration, the size of MOStransistors used in integrated circuits has been decreased to nano-scaledimensions. Such a decrease in the size of MOS transistors causesdifficulty in suppressing leak currents, which poses a problem in thatit is hard to reduce the area occupied by the circuits because of therequirements of the secure retention of necessary currents. To addressthe problem, a surrounding gate transistor (SGT) having a structure inwhich a source, a gate, and a drain are arranged vertically with respectto a substrate and the gate surrounds a pillar-shaped semiconductorlayer has been proposed (e.g., Japanese Unexamined Patent ApplicationPublication Nos. 2-71556, 2-188966, and 3-145761).

By using a metal for gate electrodes instead of a polysilicon, thedepletion can be suppressed and the resistance of the gate electrodescan be decreased. However, the production process after a metal gate isformed needs to be conducted always in consideration of metalcontamination due to the metal gate.

In existing MOS transistors, in order to perform both a metal gateprocess and a high-temperature process, a metal gate last process inwhich a metal gate is formed after a high-temperature process has beenemployed in production of actual products (IEDM 2007 K. Mistry et al.,pp. 247 to 250). The metal gate last process includes forming a gateusing a polysilicon, then depositing an interlayer insulating film,exposing the polysilicon gate by chemical mechanical polishing, etchingthe polysilicon gate, and depositing a metal. Therefore, a metal gatelast process in which a metal gate is formed after a high-temperatureprocess also needs to be employed in SGTs in order to perform both ametal gate process and a high-temperature process. In SGTs, since apillar-shaped silicon layer is located at a higher position than a gate,a scheme for employing the metal gate last process is required.

To decrease the parasitic capacitance between a gate line and asubstrate, a first insulating film is used in existing MOS transistors.For example, in the FINFET (IEDM 2010 CC. Wu et al., 27.1.1 to 27.1.4),the parasitic capacitance between a gate line and a substrate isdecreased by forming a first insulating film around a single fin-shapedsemiconductor layer and etching back the first insulating film to exposethe fin-shaped semiconductor layer. Therefore, such a first insulatingfilm also needs to be used in SGTs to decrease the parasitic capacitancebetween a gate line and a substrate. In SGTs, since a pillar-shapedsemiconductor layer is formed in addition to the fin-shapedsemiconductor layer, a scheme for forming a pillar-shaped semiconductorlayer is required.

Furthermore, FINFETs in which two transistors are formed from a singledummy pattern has been known (e.g., Japanese Unexamined PatentApplication Publication No. 2011-71235). A sidewall is formed around adummy pattern and a substrate is etched using the sidewall as a mask toform a fin, and thus two transistors are formed from a single dummypattern.

SUMMARY OF THE INVENTION

It is an object to provide a SGT production method in which theparasitic capacitance between a gate line and a substrate is decreased,a gate last process is employed, and two transistors are produced from asingle dummy pattern and a SGT structure formed by the productionmethod.

A method for producing a semiconductor device according to an aspect ofthe present invention includes:

a first step of forming, on a substrate, a first fin-shaped siliconlayer and a second fin-shaped silicon layer that are connected to eachother at their ends to form a closed loop, forming a first insulatingfilm around the first fin-shaped silicon layer and second fin-shapedsilicon layer, forming a first pillar-shaped silicon layer in an upperportion of the first fin-shaped silicon layer, and forming a secondpillar-shaped silicon layer in an upper portion of the second fin-shapedsilicon layer, the first pillar-shaped silicon layer having a widthequal to a width of the first fin-shaped silicon layer and the secondpillar-shaped silicon layer having a width equal to a width of thesecond fin-shaped silicon layer; after the first step, a second step offorming diffusion layers by implanting an impurity into an upper portionof the first pillar-shaped silicon layer, an upper portion of the firstfin-shaped silicon layer, and a lower portion of the first pillar-shapedsilicon layer and forming diffusion layers by implanting an impurityinto an upper portion of the second pillar-shaped silicon layer, anupper portion of the second fin-shaped silicon layer, and a lowerportion of the second pillar-shaped silicon layer; after the secondstep, a third step of forming a gate insulating film on and around thefirst pillar-shaped silicon layer and second pillar-shaped siliconlayer, forming a first polysilicon gate electrode and a secondpolysilicon gate electrode so as to cover the gate insulating film, andforming a polysilicon gate line, where an upper surface of a polysiliconafter the first polysilicon gate electrode, the second polysilicon gateelectrode, and the polysilicon gate line are formed is located at ahigher position than the gate insulating film on the diffusion layer inthe upper portion of the first pillar-shaped silicon layer and the gateinsulating film on the diffusion layer in the upper portion of thesecond pillar-shaped silicon layer; after the third step, a fourth stepof forming a silicide in an upper portion of the diffusion layer formedin the upper portion of the first fin-shaped silicon layer and in anupper portion of the diffusion layer formed in the second fin-shapedsilicon layer; after the fourth step, a fifth step of depositing aninterlayer insulating film, exposing the first polysilicon gateelectrode, the second polysilicon gate electrode, and the polysilicongate line, etching the first polysilicon gate electrode, the secondpolysilicon gate electrode, and the polysilicon gate line, thendepositing a metal, and forming a first metal gate electrode, a secondmetal gate electrode, and a metal gate line, the metal gate line beingconnected to the first metal gate electrode and second metal gateelectrode and extending in a direction perpendicular to a direction inwhich the first fin-shaped silicon layer and second fin-shaped siliconlayer extend; and, after the fifth step, a sixth step of forming acontact that is directly connected to the diffusion layer in the upperportion of the first pillar-shaped silicon layer and the diffusion layerin the upper portion of the second pillar-shaped silicon layer.

Preferably, the first step includes depositing a second oxide film on asubstrate in order to form a dummy pattern; forming a first resist forforming the dummy pattern; etching the second oxide film to form thedummy pattern; removing the first resist; depositing a first nitridefilm; forming a first nitride film sidewall around the dummy pattern byetching the first nitride film in such a manner that the first nitridefilm is made to remain in a sidewall shape; removing the dummy pattern;etching the substrate using the first nitride film sidewall as a mask toform the first fin-shaped silicon layer and the second fin-shapedsilicon layer that are connected to each other at their ends to form aclosed loop; forming the first insulating film around the firstfin-shaped silicon layer and second fin-shaped silicon layer; removingthe first nitride film sidewall; etching back the first insulating filmto expose an upper portion of the first fin-shaped silicon layer and anupper portion of the second fin-shaped silicon layer; forming a secondresist so as to be perpendicular to the first fin-shaped silicon layerand second fin-shaped silicon layer; etching the first fin-shapedsilicon layer and the second fin-shaped silicon layer; and removing thesecond resist to form the first pillar-shaped silicon layer such that aportion in which the first fin-shaped silicon layer is perpendicular tothe second resist is the first pillar-shaped silicon layer and to formthe second pillar-shaped silicon layer such that a portion in which thesecond fin-shaped silicon layer is perpendicular to the second resist isthe second pillar-shaped silicon layer.

Preferably, the second step performed after the first step includesdepositing a third oxide film on the entire structure formed in thefirst step; forming a second nitride film; etching the second nitridefilm in such a manner that the second nitride film is made to remain ina sidewall shape; forming the diffusion layers by implanting an impurityinto the upper portion of the first pillar-shaped silicon layer, theupper portion of the first fin-shaped silicon layer, the upper portionof the second pillar-shaped silicon layer, and the upper portion of thesecond fin-shaped silicon layer; removing the second nitride film andthe third oxide film; and performing a heat treatment.

Preferably, the third step performed after the second step includesforming the gate insulating film so as to surround silicon pillars;depositing and planarizing a polysilicon such that an upper surface ofthe planarized polysilicon is located at a higher position than the gateinsulating film on the diffusion layer formed in the upper portion ofthe first pillar-shaped silicon layer and the gate insulating film onthe diffusion layer formed in the upper portion of the secondpillar-shaped silicon layer; depositing a third nitride film; forming athird resist for forming the first polysilicon gate electrode, thesecond polysilicon gate electrode, and the polysilicon gate line;etching the third nitride film and the polysilicon to form the firstpolysilicon gate electrode, the second polysilicon gate electrode, andthe polysilicon gate line; etching the gate insulating film; andremoving the third resist.

Preferably, a fourth nitride film is deposited on the entire structureformed in the third step, the fourth nitride film is etched in such amanner that the fourth nitride film is made to remain in a sidewallshape, and a metal is deposited to form the silicide in the upperportions of the diffusion layers formed in the upper portions of thefirst fin-shaped silicon layer and second fin-shaped silicon layer.

Preferably, a fifth nitride film is deposited on the entire structureformed in the fourth step; an interlayer insulating film is depositedand planarized by chemical mechanical polishing; the first polysilicongate electrode, the second polysilicon gate electrode, and thepolysilicon gate line are exposed by chemical mechanical polishing; thefirst polysilicon gate electrode, the second polysilicon gate electrode,and the polysilicon gate line are etched; a metal is deposited to fill,with the metal, portions in which the first polysilicon gate electrode,the second polysilicon gate electrode, and the polysilicon gate linehave been present; and the metal is etched to expose the gate insulatingfilm on the diffusion layer in the upper portion of the firstpillar-shaped silicon layer and the gate insulating film on thediffusion layer in the upper portion of the second pillar-shaped siliconlayer and to form the first metal gate electrode, the second metal gateelectrode, and the metal gate line.

A semiconductor device according to another aspect of the presentinvention includes a first fin-shaped silicon layer formed on asubstrate, a second fin-shaped silicon layer formed on the substrate,the first fin-shaped silicon layer and the second fin-shaped siliconlayer being connected to each other at their ends to form a closed loop,a first insulating film formed around the first fin-shaped silicon layerand second fin-shaped silicon layer, a first pillar-shaped silicon layerformed on the first fin-shaped silicon layer and having a width equal toa width of the first fin-shaped silicon layer, a second pillar-shapedsilicon layer formed on the second fin-shaped silicon layer and having awidth equal to a width of the second fin-shaped silicon layer, adiffusion layer formed in an upper portion of the first fin-shapedsilicon layer and a lower portion of the first pillar-shaped siliconlayer, a diffusion layer formed in an upper portion of the firstpillar-shaped silicon layer, a diffusion layer formed in an upperportion of the second fin-shaped silicon layer and a lower portion ofthe second pillar-shaped silicon layer, a diffusion layer formed in anupper portion of the second pillar-shaped silicon layer, a silicideformed in upper portions of the diffusion layers formed in the upperportion of the first fin-shaped silicon layer and in the upper portionof the second fin-shaped silicon layer, a gate insulating film formedaround the first pillar-shaped silicon layer, a first metal gateelectrode formed around the gate insulating film, a gate insulating filmformed around the second pillar-shaped silicon layer, a second metalgate electrode formed around the gate insulating film, a metal gate linethat is connected to the first metal gate electrode and the second metalgate electrode and that extends in a direction perpendicular to adirection in which the first fin-shaped silicon layer and secondfin-shaped silicon layer extend, a contact formed on the diffusion layerformed in the upper portion of the first pillar-shaped silicon layer soas to be directly connected to the diffusion layer, and a contact formedon the diffusion layer formed in the upper portion of the secondpillar-shaped silicon layer so as to be directly connected to thediffusion layer.

The present invention can provide a SGT production method in which theparasitic capacitance between a gate line and a substrate is decreased,a gate last process is employed, and two transistors are produced from asingle dummy pattern and a SGT structure formed by the productionmethod.

Two SGTs can be easily produced from a single dummy pattern by employinga method for producing an existing FINFET. In the method, a sidewall isformed around a dummy pattern and a substrate is etched using thesidewall as a mask to form a fin, and thus two transistors are formedfrom a single dummy pattern.

In addition, a metal gate SGT can be easily produced because aproduction method that employs an existing metal gate last process canbe used. A silicide has been conventionally formed in an upper portionof a pillar-shaped silicon layer, but the temperature at which apolysilicon is deposited is higher than the temperature at which asilicide is formed and thus a silicide needs to be formed after theformation of a polysilicon gate. If a silicide is formed in an upperportion of a silicon pillar, a polysilicon gate is formed, a hole ismade above a polysilicon gate electrode, an insulating film is formed onthe sidewall of the hole, a silicide is formed, and the hole is filledwith an insulating film. This increases the number of production steps.Therefore, the existing metal gate last process below can be employed. Adiffusion layer is formed before the formation of a polysilicon gateelectrode and a polysilicon gate line. By covering a pillar-shapedsilicon layer with the polysilicon gate electrode and by forming asilicide only in an upper portion of a fin-shaped silicon layer, apolysilicon gate is formed. Subsequently, an interlayer insulating filmis deposited and then the polysilicon gate is exposed by chemicalmechanical polishing. The polysilicon gate is etched and then a metal isdeposited.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a plan view of a semiconductor device according to anembodiment of the present invention, FIG. 1( b) is a sectional viewtaken along line X-X′ of FIG. 1( a), and FIG. 1( c) is a sectional viewtaken along line Y-Y′ of FIG. 1( a);

FIG. 2( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 2( b)is a sectional view taken along line X-X′ of FIG. 2( a), and FIG. 2( c)is a sectional view taken along line Y-Y′ of FIG. 2( a);

FIG. 3( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 3( b)is a sectional view taken along line X-X′ of FIG. 3( a), and FIG. 3( c)is a sectional view taken along line Y-Y′ of FIG. 3( a);

FIG. 4( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 4( b)is a sectional view taken along line X-X′ of FIG. 4( a), and FIG. 4( c)is a sectional view taken along line Y-Y′ of FIG. 4( a);

FIG. 5( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 5( b)is a sectional view taken along line X-X′ of FIG. 5( a), and FIG. 5( c)is a sectional view taken along line Y-Y′ of FIG. 5( a);

FIG. 6( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 6( b)is a sectional view taken along line X-X′ of FIG. 6( a), and FIG. 6( c)is a sectional view taken along line Y-Y′ of FIG. 6( a);

FIG. 7( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 7( b)is a sectional view taken along line X-X′ of FIG. 7( a), and FIG. 7( c)is a sectional view taken along line Y-Y′ of FIG. 7( a);

FIG. 8( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 8( b)is a sectional view taken along line X-X′ of FIG. 8( a), and FIG. 8( c)is a sectional view taken along line Y-Y′ of FIG. 8( a);

FIG. 9( a) is a plan view showing a method for producing a semiconductordevice according to an embodiment of the present invention, FIG. 9( b)is a sectional view taken along line X-X′ of FIG. 9( a), and FIG. 9( c)is a sectional view taken along line Y-Y′ of FIG. 9( a);

FIG. 10( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 10( b) is a sectional view taken along line X-X′ of FIG.10( a), and FIG. 10( c) is a sectional view taken along line Y-Y′ ofFIG. 10( a);

FIG. 11( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 11( b) is a sectional view taken along line X-X′ of FIG.11( a), and FIG. 11( c) is a sectional view taken along line Y-Y′ ofFIG. 11( a);

FIG. 12( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 12( b) is a sectional view taken along line X-X′ of FIG.12( a), and FIG. 12( c) is a sectional view taken along line Y-Y′ ofFIG. 12( a);

FIG. 13( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 13( b) is a sectional view taken along line X-X′ of FIG.13( a), and FIG. 13( c) is a sectional view taken along line Y-Y′ ofFIG. 13( a);

FIG. 14( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 14( b) is a sectional view taken along line X-X′ of FIG.14( a), and FIG. 14( c) is a sectional view taken along line Y-Y′ ofFIG. 14( a);

FIG. 15( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 15( b) is a sectional view taken along line X-X′ of FIG.15( a), and FIG. 15( c) is a sectional view taken along line Y-Y′ ofFIG. 15( a);

FIG. 16( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 16( b) is a sectional view taken along line X-X′ of FIG.16( a), and FIG. 16( c) is a sectional view taken along line Y-Y′ ofFIG. 16( a);

FIG. 17( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 17( b) is a sectional view taken along line X-X′ of FIG.17( a), and FIG. 17( c) is a sectional view taken along line Y-Y′ ofFIG. 17( a);

FIG. 18( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 18( b) is a sectional view taken along line X-X′ of FIG.18( a), and FIG. 18( c) is a sectional view taken along line Y-Y′ ofFIG. 18( a);

FIG. 19( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 19( b) is a sectional view taken along line X-X′ of FIG.19( a), and FIG. 19( c) is a sectional view taken along line Y-Y′ ofFIG. 19( a);

FIG. 20( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 20( b) is a sectional view taken along line X-X′ of FIG.20( a), and FIG. 20( c) is a sectional view taken along line Y-Y′ ofFIG. 20( a);

FIG. 21( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 21( b) is a sectional view taken along line X-X′ of FIG.21( a), and FIG. 21( c) is a sectional view taken along line Y-Y′ ofFIG. 21( a);

FIG. 22( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 22( b) is a sectional view taken along line X-X′ of FIG.22( a), and FIG. 22( c) is a sectional view taken along line Y-Y′ ofFIG. 22( a);

FIG. 23( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 23( b) is a sectional view taken along line X-X of FIG.23( a), and FIG. 23( c) is a sectional view taken along line Y-Y′ ofFIG. 23( a);

FIG. 24( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 24( b) is a sectional view taken along line X-X′ of FIG.24( a), and FIG. 24( c) is a sectional view taken along line Y-Y′ ofFIG. 24( a);

FIG. 25( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 25( b) is a sectional view taken along line X-X′ of FIG.25( a), and FIG. 25( c) is a sectional view taken along line Y-Y′ ofFIG. 25( a);

FIG. 26( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 26( b) is a sectional view taken along line X-X′ of FIG.26( a), and FIG. 26( c) is a sectional view taken along line Y-Y′ ofFIG. 26( a);

FIG. 27( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 27( b) is a sectional view taken along line X-X′ of FIG.27( a), and FIG. 27( c) is a sectional view taken along line Y-Y′ ofFIG. 27( a);

FIG. 28( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 28( b) is a sectional view taken along line X-X′ of FIG.28( a), and FIG. 28( c) is a sectional view taken along line Y-Y′ ofFIG. 28( a);

FIG. 29( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 29( b) is a sectional view taken along line X-X′ of FIG.29( a), and FIG. 29( c) is a sectional view taken along line Y-Y′ ofFIG. 29( a);

FIG. 30( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 30( b) is a sectional view taken along line X-X′ of FIG.30( a), and FIG. 30( c) is a sectional view taken along line Y-Y′ ofFIG. 30( a);

FIG. 31( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 31( b) is a sectional view taken along line X-X′ of FIG.31( a), and FIG. 31( c) is a sectional view taken along line Y-Y′ ofFIG. 31( a);

FIG. 32( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 32( b) is a sectional view taken along line X-X′ of FIG.32( a), and FIG. 32( c) is a sectional view taken along line Y-Y′ ofFIG. 32( a);

FIG. 33( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 33( b) is a sectional view taken along line X-X′ of FIG.33( a), and FIG. 33( c) is a sectional view taken along line Y-Y′ ofFIG. 33( a);

FIG. 34( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 34( b) is a sectional view taken along line X-X of FIG.34( a), and FIG. 34( c) is a sectional view taken along line Y-Y′ ofFIG. 34( a);

FIG. 35( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 35( b) is a sectional view taken along line X-X′ of FIG.35( a), and FIG. 35( c) is a sectional view taken along line Y-Y′ ofFIG. 35( a);

FIG. 36( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 36( b) is a sectional view taken along line X-X′ of FIG.36( a), and FIG. 36( c) is a sectional view taken along line Y-Y’ ofFIG. 36( a);

FIG. 37( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 37( b) is a sectional view taken along line X-X′ of FIG.37( a), and FIG. 37( c) is a sectional view taken along line Y-Y′ ofFIG. 37( a);

FIG. 38( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 38( b) is a sectional view taken along line X-X′ of FIG.38( a), and FIG. 38( c) is a sectional view taken along line Y-Y′ ofFIG. 38( a);

FIG. 39( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 39( b) is a sectional view taken along line X-X′ of FIG.39( a), and FIG. 39( c) is a sectional view taken along line Y-Y′ ofFIG. 39( a);

FIG. 40( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 40( b) is a sectional view taken along line X-X′ of FIG.40( a), and FIG. 40( c) is a sectional view taken along line Y-Y′ ofFIG. 40( a);

FIG. 41( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 41( b) is a sectional view taken along line X-X′ of FIG.41( a), and FIG. 41( c) is a sectional view taken along line Y-Y′ ofFIG. 41( a);

FIG. 42( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 42( b) is a sectional view taken along line X-X of FIG.42( a), and FIG. 42( c) is a sectional view taken along line Y-Y′ ofFIG. 42( a);

FIG. 43( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 43( b) is a sectional view taken along line X-X′ of FIG.43( a), and FIG. 43( c) is a sectional view taken along line Y-Y′ ofFIG. 43( a);

FIG. 44( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 44( b) is a sectional view taken along line X-X′ of FIG.44( a), and FIG. 44( c) is a sectional view taken along line Y-Y′ ofFIG. 44( a);

FIG. 45( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 45( b) is a sectional view taken along line X-X′ of FIG.45( a), and FIG. 45( c) is a sectional view taken along line Y-Y′ ofFIG. 45( a);

FIG. 46( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 46( b) is a sectional view taken along line X-X′ of FIG.46( a), and FIG. 46( c) is a sectional view taken along line Y-Y′ ofFIG. 46( a); and

FIG. 47( a) is a plan view showing a method for producing asemiconductor device according to an embodiment of the presentinvention, FIG. 47( b) is a sectional view taken along line X-X′ of FIG.47( a), and FIG. 47( c) is a sectional view taken along line Y-Y′ ofFIG. 47( a).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A production process for forming a SGT structure according to anembodiment of the present invention will now be described with referenceto FIGS. 2 to 47.

A production method is described that includes forming a firstfin-shaped silicon layer and a second fin-shaped silicon layer on asubstrate, forming a first insulating film around the first fin-shapedsilicon layer and second fin-shaped silicon layer, forming a firstpillar-shaped silicon layer in an upper portion of the first fin-shapedsilicon layer, and forming a second pillar-shaped silicon layer in anupper portion of the second fin-shaped silicon layer. As shown in FIG.2, a second oxide film 102 is deposited on a silicon substrate 101 inorder to form a dummy pattern. A nitride film or a laminated film of anoxide film and a polysilicon may be used.

As shown in FIG. 3, a first resist 103 for forming the dummy pattern isformed.

As shown in FIG. 4, the second oxide film 102 is etched to form thedummy pattern 102.

As shown in FIG. 5, the first resist 103 is removed.

As shown in FIG. 6, a first nitride film 104 is deposited.

As shown in FIG. 7, by etching the first nitride film 104, the firstnitride film 104 is made to remain in a sidewall shape. Thus, a firstnitride film sidewall 104 is formed around the dummy pattern 102. Byetching silicon using the formed first nitride film sidewall 104, afirst fin-shaped silicon layer 105 and a second fin-shaped silicon layer106 that are connected to each other at their ends to form a closed loopwill be formed.

As shown in FIG. 8, the dummy pattern 102 is removed.

As shown in FIG. 9, by etching the silicon substrate 101 using the firstnitride film sidewall 104 as a mask, a first fin-shaped silicon layer105 and a second fin-shaped silicon layer 106 that are connected to eachother at their ends to form a loop are formed.

As shown in FIG. 10, a first insulating film 107 is formed around thefirst fin-shaped silicon layer 105 and second fin-shaped silicon layer106.

An oxide film formed using high-density plasma or an oxide film formedby low-pressure chemical vapor deposition may be used as the firstinsulating film.

As shown in FIG. 11, the first nitride film sidewall 104 is removed. Inthe case where the first nitride film sidewall 104 is removed during thesilicon etching or the oxide film deposition, this step is skipped.

As shown in FIG. 12, the first insulating film 107 is etched back toexpose an upper portion of the first fin-shaped silicon layer 105 and anupper portion of the second fin-shaped silicon layer 106.

As shown in FIG. 13, a second resist 108 is formed so as to beperpendicular to the first fin-shaped silicon layer 105 and secondfin-shaped silicon layer 106. The portions in which the first fin-shapedsilicon layer 105 and second fin-shaped silicon layer 106 areperpendicular to the resist 108 are portions to be formed intopillar-shaped silicon layers. Since the resist can be formed linearly,there is a low probability of the resist falling over after thepatterning. Consequently, the process can be stably performed.

As shown in FIG. 14, the first fin-shaped silicon layer 105 and thesecond fin-shaped silicon layer 106 are etched. The portion in which thefirst fin-shaped silicon layer 105 is perpendicular to the second resist108 becomes a first pillar-shaped silicon layer 109. The portion inwhich the second fin-shaped silicon layer 106 is perpendicular to thesecond resist 108 becomes a second pillar-shaped silicon layer 110.Therefore, the first pillar-shaped silicon layer 109 has a width equalto the width of the first fin-shaped silicon layer 105. The secondpillar-shaped silicon layer 110 has a width equal to the width of thesecond fin-shaped silicon layer 106.

As a result, a structure is formed in which the first pillar-shapedsilicon layer 109 is formed in the upper portion of the first fin-shapedsilicon layer 105, the second pillar-shaped silicon layer 110 is formedin the upper portion of the second fin-shaped silicon layer 106, and thefirst insulating film 107 is formed around the first fin-shaped siliconlayer 105 and second fin-shaped silicon layer 106.

As shown in FIG. 15, the second resist 108 is removed.

Next, there is described a production method that includes, in order toachieve gate last, forming diffusion layers by implanting an impurityinto an upper portion of the first pillar-shaped silicon layer 109, anupper portion of the first fin-shaped silicon layer 105, and a lowerportion of the first pillar-shaped silicon layer 109 and formingdiffusion layers by implanting an impurity into an upper portion of thesecond pillar-shaped silicon layer 110, an upper portion of the secondfin-shaped silicon layer 106, and a lower portion of the secondpillar-shaped silicon layer 110.

As shown in FIG. 16, a third oxide film 111 is deposited and a secondnitride film 112 is formed. Since the upper portions of thepillar-shaped silicon layers will be covered with a gate insulating filmand a polysilicon gate electrode later, diffusion layers are formed inthe upper portions of the pillar-shaped silicon layers before coveredwith the gate insulating film and polysilicon gate electrode.

As shown in FIG. 17, by etching the second nitride film 112, the secondnitride film 112 is made to remain in a sidewall shape.

As shown in FIG. 18, an impurity such as arsenic, phosphorus, or boronis implanted to form a diffusion layer 113 in the upper portion of thefirst pillar-shaped silicon layer 109, diffusion layers 115 and 116 inthe upper portions of the first fin-shaped silicon layer 105, adiffusion layer 114 in the upper portion of the second pillar-shapedsilicon layer 110, and diffusion layers 115 and 116 in the upperportions of the second fin-shaped silicon layer 106.

As shown in FIG. 19, the second nitride film 112 and the third oxidefilm 111 are removed.

As shown in FIG. 20, a heat treatment is performed. The diffusion layers115 and 116 in the upper portions of the first fin-shaped silicon layer105 and second fin-shaped silicon layer 106 are brought into contactwith each other and thus a diffusion layer 117 is formed. In order toachieve gate last, the diffusion layers 113 and 117 are formed byimplanting an impurity into the upper portion of the first pillar-shapedsilicon layer 109, the upper portion of the first fin-shaped siliconlayer 105, and the lower portion of the first pillar-shaped siliconlayer 109; and the diffusion layers 114 and 117 are formed by implantingan impurity into the upper portion of the second pillar-shaped siliconlayer 110, the upper portion of the second fin-shaped silicon layer 106,and the lower portion of the second pillar-shaped silicon layer 110.

Next, there is described a production method that includes, in order toachieve gate last, forming a first polysilicon gate electrode 119 b, asecond polysilicon gate electrode 119 a, and a polysilicon gate line 119c using a polysilicon. To achieve gate last, an interlayer insulatingfilm is deposited and then polysilicon gate electrodes and a polysilicongate line are exposed by chemical mechanical polishing. Therefore, theupper portions of the pillar-shaped silicon layers need to be preventedfrom being exposed by the chemical mechanical polishing.

As shown in FIG. 21, a gate insulating film 118 is formed and apolysilicon 119 is deposited and planarized. The upper surface of theplanarized polysilicon 119 is located at a higher position than the gateinsulating film 118 on the diffusion layer 113 formed in the upperportion of the first pillar-shaped silicon layer 109 and the gateinsulating film 118 on the diffusion layer 114 formed in the upperportion of the second pillar-shaped silicon layer 110. Thus, when theinterlayer insulating film is deposited and then the polysilicon gateelectrodes and polysilicon gate line are exposed by chemical mechanicalpolishing in order to achieve gate last, the upper portions of thepillar-shaped silicon layers can be prevented from being exposed bychemical mechanical polishing.

A third nitride film 120 is deposited. The third nitride film 120 is afilm that, when a silicide is formed in the upper portions of the firstfin-shaped silicon layer 105 and second fin-shaped silicon layer 106,prevents the formation of the silicide in upper portions of a firstpolysilicon gate electrode 119 b, a second polysilicon gate electrode119 a, and a polysilicon gate line 119 c.

As shown in FIG. 22, a third resist 121 for forming a first polysilicongate electrode 119 b, a second polysilicon gate electrode 119 a, and apolysilicon gate line 119 c is formed. A portion to be the gate line isdesirably perpendicular to the first fin-shaped silicon layer 105 andsecond fin-shaped silicon layer 106 to decrease the parasiticcapacitance between the gate line and the substrate.

As shown in FIG. 23, the third nitride film 120 is etched and thepolysilicon 119 is etched to form a first polysilicon gate electrode 119b, a second polysilicon gate electrode 119 a, and a polysilicon gateline 119 c.

As shown in FIG. 24, the gate insulating film 118 is etched.

As shown in FIG. 25, the third resist 121 is removed.

The production method that includes, in order to achieve gate last,forming a first polysilicon gate electrode 119 b, a second polysilicongate electrode 119 a, and a polysilicon gate line 119 c using apolysilicon has been described. The upper surface of the polysiliconafter the first polysilicon gate electrode 119 b, second polysilicongate electrode 119 a, and polysilicon gate line 119 c are formed islocated at a higher position than the gate insulating film 118 on thediffusion layer 113 formed in the upper portion of the firstpillar-shaped silicon layer 109 and the gate insulating film 118 on thediffusion layer 114 formed in the upper portion of the secondpillar-shaped silicon layer 110.

Next, there is described a production method that includes forming asilicide in the upper portion of the diffusion layer 117 formed in theupper portion of the first fin-shaped silicon layer 105 and in the upperportion of the diffusion layer 117 formed in the upper portion of thesecond fin-shaped silicon layer 106.

This production method is characterized in that a silicide is not formedin upper portions of the first polysilicon gate electrode 119 b, secondpolysilicon gate electrode 119 a, and polysilicon gate line 119 c and inupper portions of the diffusion layer 113 formed in the upper portion ofthe first pillar-shaped silicon layer 109 and the diffusion layer 114formed in the upper portion of the second pillar-shaped silicon layer110. If a silicide is formed in the upper portions of the diffusionlayer 113 formed in the upper portion of the first pillar-shaped siliconlayer 109 and the diffusion layer 114 formed in the upper portion of thesecond pillar-shaped silicon layer 110, the number of production stepsis increased.

As shown in FIG. 26, a fourth nitride film 122 is deposited.

As shown in FIG. 27, by etching the fourth nitride film 122, the fourthnitride film 122 is made to remain in a sidewall shape.

As shown in FIG. 28, a metal such as nickel or cobalt is deposited toform a silicide 123 in upper portions of the diffusion layers 117 formedin the upper portions of the first fin-shaped silicon layer 105 andsecond fin-shaped silicon layer 106. Herein, a silicide is not formed inupper portions of the first polysilicon gate electrode 119 b, secondpolysilicon gate electrode 119 a, and polysilicon gate line 119 cbecause the first polysilicon gate electrode 119 b, second polysilicongate electrode 119 a, and polysilicon gate line 119 c are covered withthe fourth nitride film 122 and the third nitride film 120. A silicideis also not formed in upper portions of the diffusion layer 113 formedin the upper portion of the first pillar-shaped silicon layer 109 andthe diffusion layer 114 formed in the upper portion of the secondpillar-shaped silicon layer 110 because the diffusion layer 113 and thediffusion layer 114 are covered with the gate insulating film 118, thefirst polysilicon gate electrode 119 b, the second polysilicon gateelectrode 119 a, and the polysilicon gate line 119 c.

The production method that includes forming a silicide in the upperportion of the diffusion layer 117 formed in the upper portion of thefirst fin-shaped silicon layer 105 and forming a silicide in the upperportion of the diffusion layer 117 formed in the upper portion of thesecond fin-shaped silicon layer 106 has been described.

Next, there is described a production method of gate last that includesdepositing an interlayer insulating film 125, exposing the firstpolysilicon gate electrode 119 b, second polysilicon gate electrode 119a, and polysilicon gate line 119 c, etching the first polysilicon gateelectrode 119 b, second polysilicon gate electrode 119 a, andpolysilicon gate line 119 c, depositing a metal 126, and forming a firstmetal gate electrode 126 b, a second metal gate electrode 126 a, and ametal gate line 126 c.

As shown in FIG. 29, a fifth nitride film 124 is deposited in order toprotect the silicide 123.

As shown in FIG. 30, an interlayer insulating film 125 is deposited andplanarized by chemical mechanical polishing.

As shown in FIG. 31, the first polysilicon gate electrode 119 b, secondpolysilicon gate electrode 119 a, and polysilicon gate line 119 c areexposed by chemical mechanical polishing.

As shown in FIG. 32, the first polysilicon gate electrode 119 b, secondpolysilicon gate electrode 119 a, and polysilicon gate line 119 c areetched. This etching is desirably performed by wet etching.

As shown in FIG. 33, a metal 126 is deposited and planarized to fill,with the metal 126, the portions in which the first polysilicon gateelectrode 119 b, second polysilicon gate electrode 119 a, andpolysilicon gate line 119 c have been present. Atomic layer depositionis preferably used.

As shown in FIG. 34, the metal 126 is etched to expose the gateinsulating film 118 on the diffusion layer 113 in the upper portion ofthe first pillar-shaped silicon layer 109 and the gate insulating film118 on the diffusion layer 114 in the upper portion of the secondpillar-shaped silicon layer 110. As a result, a first metal gateelectrode 126 b, a second metal gate electrode 126 a, and a metal gateline 126 c are formed.

The production method of gate last that includes depositing theinterlayer insulating film 125, exposing the first polysilicon gateelectrode 119 b, second polysilicon gate electrode 119 a, andpolysilicon gate line 119 c, etching the first polysilicon gateelectrode 119 b, second polysilicon gate electrode 119 a, andpolysilicon gate line 119 c, depositing the metal 126, and forming thefirst metal gate electrode 126 b, the second metal gate electrode 126 a,and the metal gate line 126 c has been described.

Next, there is described a production method for forming contacts. Sincethe silicide is not formed in the upper portions of the diffusion layer113 formed in the upper portion of the first pillar-shaped silicon layer109 and the diffusion layer 114 formed in the upper portion of thesecond pillar-shaped silicon layer 110, a contact is directly connectedto the diffusion layer 113 in the upper portion of the firstpillar-shaped silicon layer 109 and another contact is directlyconnected to the diffusion layer 114 in the upper portion of the secondpillar-shaped silicon layer 110.

As shown in FIG. 35, an interlayer insulating film 127 is deposited andplanarized.

As shown in FIG. 36, a fourth resist 128 for making a contact hole abovethe first pillar-shaped silicon layer 109 and second pillar-shapedsilicon layer 110 is formed.

As shown in FIG. 37, a contact hole 129 is made by etching theinterlayer insulating film 127.

As shown in FIG. 38, the fourth resist 128 is removed.

As shown in FIG. 39, a fifth resist 130 for making contact holes abovethe metal gate line 126 c and above the first fin-shaped silicon layer105 and second fin-shaped silicon layer 106 is formed.

As shown in FIG. 40, contact holes 131 and 132 are made by etching theinterlayer insulating films 127 and 125, respectively.

As shown in FIG. 41, the fifth resist 130 is removed.

As shown in FIG. 42, the fifth nitride film 124 and the gate insulatingfilm 118 are etched to expose the silicide 123 and the diffusion layers113 and 114, respectively.

As shown in FIG. 43, a metal is deposited to form contacts 133, 134, and135. The production method for forming contacts has been described.Since the silicide is not formed in the upper portions of the diffusionlayer 113 formed in the upper portion of the first pillar-shaped siliconlayer 109 and the diffusion layer 114 in the upper portion of the secondpillar-shaped silicon layer 110, the contact 134 is directly connectedto the diffusion layer 113 in the upper portion of the firstpillar-shaped silicon layer 109 and the other contact 134 is directlyconnected to the diffusion layer 114 in the upper portion of the secondpillar-shaped silicon layer 110.

Next, there is described a production method for forming metal wirelayers.

As shown in FIG. 44, a metal 136 is deposited.

As shown in FIG. 45, sixth resists 137, 138, and 139 for forming metalwires are formed.

As shown in 46, the metal 136 is etched to form metal wires 140, 141,and 142.

As shown in FIG. 47, the sixth resists 137, 138, and 139 are removed.

The production method for forming metal wire layers has been described.

FIG. 1 shows a SGT structure formed by the above-described productionmethod.

The SGT structure includes a first fin-shaped silicon layer 105 formedon a substrate 101 and a second fin-shaped silicon layer 106 formed onthe substrate 101, the first fin-shaped silicon layer 105 and the secondfin-shaped silicon layer 106 being connected to each other at their endsto form a closed loop; a first insulating film 107 formed around thefirst fin-shaped silicon layer 105 and second fin-shaped silicon layer106; a first pillar-shaped silicon layer 109 formed in an upper portionof the fin-shaped silicon layer 105 and a second pillar-shaped siliconlayer 110 formed in an upper portion of the second fin-shaped siliconlayer 106, the first pillar-shaped silicon layer 109 having a widthequal to the width of the first fin-shaped silicon layer 105 and thesecond pillar-shaped silicon layer 110 having a width equal to the widthof the second fin-shaped silicon layer 106; a diffusion layer 117 formedin an upper portion of the first fin-shaped silicon layer 105 and alower portion of the first pillar-shaped silicon layer 109, a diffusionlayer 113 formed in an upper portion of the first pillar-shaped siliconlayer 109, a diffusion layer 117 formed in an upper portion of thesecond fin-shaped silicon layer 106 and a lower portion of the secondpillar-shaped silicon layer 110, and a diffusion layer 114 formed in anupper portion of the second pillar-shaped silicon layer 110; a silicide123 formed in upper portions of the diffusion layers 117 formed in theupper portion of the first fin-shaped silicon layer 105 and in the upperportion of the second fin-shaped silicon layer 106; a gate insulatingfilm 118 formed around the first pillar-shaped silicon layer 109, afirst metal gate electrode 126 b formed around the gate insulating film118, a gate insulating film 118 formed around the second pillar-shapedsilicon layer 110, a second metal gate electrode 126 a formed around thegate insulating film 118, and a metal gate line 126 c that is connectedto the first metal gate electrode 126 b and the second metal gateelectrode 126 a and that extends in a direction perpendicular to thedirection in which the first fin-shaped silicon layer 105 and secondfin-shaped silicon layer 106 extend; and a contact 134 formed on thediffusion layer 113 formed in the upper portion of the firstpillar-shaped silicon layer 109 so as to be directly connected to thediffusion layer 113 and a contact 134 formed on the diffusion layer 114formed in the upper portion of the second pillar-shaped silicon layer110 so as to be directly connected to the diffusion layer 114.

Accordingly, there are provided a SGT production method in which theparasitic capacitance between a gate line and a substrate is decreased,a gate last process is employed, and two transistors are produced from asingle dummy pattern and a SGT structure formed by the productionmethod.

What is claimed is:
 1. A method for producing a semiconductor device,comprising a first step of forming, on a substrate, a first fin-shapedsilicon layer and a second fin-shaped silicon layer that are connectedto each other at their ends to form a closed loop, forming a firstinsulating film around the first fin-shaped silicon layer and secondfin-shaped silicon layer, forming a first pillar-shaped silicon layer inan upper portion of the first fin-shaped silicon layer, and forming asecond pillar-shaped silicon layer in an upper portion of the secondfin-shaped silicon layer, the first pillar-shaped silicon layer having awidth equal to a width of the first fin-shaped silicon layer and thesecond pillar-shaped silicon layer having a width equal to a width ofthe second fin-shaped silicon layer; after the first step, a second stepof forming diffusion layers by implanting an impurity into an upperportion of the first pillar-shaped silicon layer, an upper portion ofthe first fin-shaped silicon layer, and a lower portion of the firstpillar-shaped silicon layer and forming diffusion layers by implantingan impurity into an upper portion of the second pillar-shaped siliconlayer, an upper portion of the second fin-shaped silicon layer, and alower portion of the second pillar-shaped silicon layer; after thesecond step, a third step of forming a gate insulating film on andaround the first pillar-shaped silicon layer and second pillar-shapedsilicon layer, forming a first polysilicon gate electrode and a secondpolysilicon gate electrode so as to cover the gate insulating film, andforming a polysilicon gate line, where an upper surface of a polysiliconafter the first polysilicon gate electrode, the second polysilicon gateelectrode, and the polysilicon gate line are formed is located at ahigher position than the gate insulating film on the diffusion layer inthe upper portion of the first pillar-shaped silicon layer and the gateinsulating film on the diffusion layer in the upper portion of thesecond pillar-shaped silicon layer; after the third step, a fourth stepof forming a silicide in an upper portion of the diffusion layer formedin the upper portion of the first fin-shaped silicon layer and in anupper portion of the diffusion layer formed in the second fin-shapedsilicon layer; after the fourth step, a fifth step of depositing aninterlayer insulating film, exposing the first polysilicon gateelectrode, the second polysilicon gate electrode, and the polysilicongate line, etching the first polysilicon gate electrode, the secondpolysilicon gate electrode, and the polysilicon gate line, thendepositing a metal, and forming a first metal gate electrode, a secondmetal gate electrode, and a metal gate line, the metal gate line beingconnected to the first metal gate electrode and second metal gateelectrode and extending in a direction perpendicular to a direction inwhich the first fin-shaped silicon layer and second fin-shaped siliconlayer extend; and, after the fifth step, a sixth step of forming acontact that is directly connected to the diffusion layer in the upperportion of the first pillar-shaped silicon layer and the diffusion layerin the upper portion of the second pillar-shaped silicon layer.
 2. Themethod for producing a semiconductor device according to claim 1,wherein the first step includes depositing a second oxide film on asubstrate in order to form a dummy pattern; forming a first resist forforming the dummy pattern; etching the second oxide film to form thedummy pattern; removing the first resist; depositing a first nitridefilm; forming a first nitride film sidewall around the dummy pattern byetching the first nitride film in such a manner that the first nitridefilm is made to remain in a sidewall shape; removing the dummy pattern;etching the substrate using the first nitride film sidewall as a mask toform the first fin-shaped silicon layer and the second fin-shapedsilicon layer that are connected to each other at their ends to form aclosed loop; forming the first insulating film around the firstfin-shaped silicon layer and second fin-shaped silicon layer; removingthe first nitride film sidewall; etching back the first insulating filmto expose an upper portion of the first fin-shaped silicon layer and anupper portion of the second fin-shaped silicon layer; forming a secondresist so as to be perpendicular to the first fin-shaped silicon layerand second fin-shaped silicon layer; etching the first fin-shapedsilicon layer and the second fin-shaped silicon layer; and removing thesecond resist to form the first pillar-shaped silicon layer such that aportion in which the first fin-shaped silicon layer is perpendicular tothe second resist is the first pillar-shaped silicon layer and to formthe second pillar-shaped silicon layer such that a portion in which thesecond fin-shaped silicon layer is perpendicular to the second resist isthe second pillar-shaped silicon layer.
 3. The method for producing asemiconductor device according to claim 1, wherein the second stepperformed after the first step includes depositing a third oxide film onthe entire structure formed in the first step; forming a second nitridefilm; etching the second nitride film in such a manner that the secondnitride film is made to remain in a sidewall shape; forming thediffusion layers by implanting an impurity into the upper portion of thefirst pillar-shaped silicon layer, the upper portion of the firstfin-shaped silicon layer, the upper portion of the second pillar-shapedsilicon layer, and the upper portion of the second fin-shaped siliconlayer; removing the second nitride film and the third oxide film; andperforming a heat treatment.
 4. The method for producing a semiconductordevice according to claim 1, wherein the third step performed after thesecond step includes forming the gate insulating film so as to surroundsilicon pillars; depositing and planarizing a polysilicon such that anupper surface of the planarized polysilicon is located at a higherposition than the gate insulating film on the diffusion layer formed inthe upper portion of the first pillar-shaped silicon layer and the gateinsulating film on the diffusion layer formed in the upper portion ofthe second pillar-shaped silicon layer; depositing a third nitride film;forming a third resist for forming the first polysilicon gate electrode,the second polysilicon gate electrode, and the polysilicon gate line;etching the third nitride film and the polysilicon to form the firstpolysilicon gate electrode, the second polysilicon gate electrode, andthe polysilicon gate line; etching the gate insulating film; andremoving the third resist.
 5. The method for producing a semiconductordevice according to claim 4, wherein a fourth nitride film is depositedon the entire structure formed in the third step, the fourth nitridefilm is etched in such a manner that the fourth nitride film is made toremain in a sidewall shape, and a metal is deposited to form thesilicide in the upper portions of the diffusion layers formed in theupper portions of the first fin-shaped silicon layer and secondfin-shaped silicon layer.
 6. The method for producing a semiconductordevice according to claim 5, wherein a fifth nitride film is depositedon the entire structure formed in the fourth step; an interlayerinsulating film is deposited and planarized by chemical mechanicalpolishing; the first polysilicon gate electrode, the second polysilicongate electrode, and the polysilicon gate line are exposed by chemicalmechanical polishing; the first polysilicon gate electrode, the secondpolysilicon gate electrode, and the polysilicon gate line are etched; ametal is deposited to fill, with the metal, portions in which the firstpolysilicon gate electrode, the second polysilicon gate electrode, andthe polysilicon gate line have been present; and the metal is etched toexpose the gate insulating film on the diffusion layer in the upperportion of the first pillar-shaped silicon layer and the gate insulatingfilm on the diffusion layer in the upper portion of the secondpillar-shaped silicon layer and to form the first metal gate electrode,the second metal gate electrode, and the metal gate line.
 7. Asemiconductor device comprising a first fin-shaped silicon layer formedon a substrate, a second fin-shaped silicon layer formed on thesubstrate, the first fin-shaped silicon layer and the second fin-shapedsilicon layer being connected to each other at their ends to form aclosed loop, a first insulating film formed around the first fin-shapedsilicon layer and second fin-shaped silicon layer, a first pillar-shapedsilicon layer formed on the first fin-shaped silicon layer and having awidth equal to a width of the first fin-shaped silicon layer, a secondpillar-shaped silicon layer formed on the second fin-shaped siliconlayer and having a width equal to a width of the second fin-shapedsilicon layer, a diffusion layer formed in an upper portion of the firstfin-shaped silicon layer and a lower portion of the first pillar-shapedsilicon layer, a diffusion layer formed in an upper portion of the firstpillar-shaped silicon layer, a diffusion layer formed in an upperportion of the second fin-shaped silicon layer and a lower portion ofthe second pillar-shaped silicon layer, a diffusion layer formed in anupper portion of the second pillar-shaped silicon layer, a silicideformed in upper portions of the diffusion layers formed in the upperportion of the first fin-shaped silicon layer and in the upper portionof the second fin-shaped silicon layer, a gate insulating film formedaround the first pillar-shaped silicon layer, a first metal gateelectrode formed around the gate insulating film, a gate insulating filmformed around the second pillar-shaped silicon layer, a second metalgate electrode formed around the gate insulating film, a metal gate linethat is connected to the first metal gate electrode and the second metalgate electrode and that extends in a direction perpendicular to adirection in which the first fin-shaped silicon layer and secondfin-shaped silicon layer extend, a contact formed on the diffusion layerformed in the upper portion of the first pillar-shaped silicon layer soas to be directly connected to the diffusion layer, and a contact formedon the diffusion layer formed in the upper portion of the secondpillar-shaped silicon layer so as to be directly connected to thediffusion layer.